EFIDynoTuning Forum

OK.

How do I calculate/adjust the base parameters (low & high slope, breakpoint, offset) based on increasing my fuel pressure from 43.5psi to 55 psi?

Sean

I'm about to ask a question(s) that I should know the answer to but I just can't find the answer in my tuning log notes.

I'd like to prepare an alternative tune that uses different (Continental) injector data for my Deka V 80 lb/hr 'shorty' injectors. I have them installed and running using the Ford Racing M-9593-LU80 (Deka IV) injector data that's provided on this site but I think the difference between what I'm using and what Continental provides may end up working better.

The Ford Racing data lists injector parameters (slope, breakpoint, offset) at base fuel pressure of 39.15 psi and then provides compensation values that are intended to be multiplied against those base parameters to match the actual FP you're using. My base FP is 55psi, so the calculation looks something like this:
base ALOSL (101.459) x 55 psi compensation factor (1.2271) = adjusted ALOSL (124.5)
base AHISL (75.157) x 55 psi compensation factor (1.1883) = adjusted AHISL (89.309)
base breakpoint (0.00002421) x 55 psi compensation factor (1.121) = adjusted breakpoint (0.00002713941)
base voltage offset table values x 55 psi compensation factor (1.1848) = adjusted voltage offset table

Can I use these same multipliers (55 psi 'compensation factors' in bold above) with the Continental base parameters? To further confuse the issue for me, Continental base injector parameters are provided at 43.5 psi FP, unlike the Ford Racing data which uses 39.15 psi FP.

Can anyone help me sort through this?

Thanks,

Sean

When modifying the default (A9L2) y axis values for FN348 ( 19/(new injector size) * (new engine size)/302=0.xxx Apply that 0.xxx correction to the entire y axis.) am I supposed to use the nominal high slope injector size I am using (80 lb/hr at 39.15lbs FP) or the FP adjusted size? Should I insert the FP adjusted high slope of 89.309 or the nominal 80 lb/hr into the equation? Does it matter? If not, please explain.

Sean

Edit: corrected FN # in title.

You've got it, just a spreadsheet I created listing the 80lb/hr injector base data I took from this website and then a simple calculating section that multiplies those base values by the compensation factor provided based on my actual fuel pressure (55 psi). If you need to do the same for 60 psi FP, the next cell down from the 55 psi (highlighted) compensation factors I used are probably the ones you'd want to use. I'm no qualified enough to tell you how the compensation values work with base injector information other than the Ford Racing ones I started with.

I'm still waiting to see how the Continental injector data works for you! Do share when you get the chance.

Sean

I’d love to hear how the Continental supplied data works for you. Please share your results when you’re able.

Sean

Interesting. I have the dark red (burgundy) color 80 lb/hr Siemens-Deka (shorty) injectors and was told to use the the M-9593-LU80 calibration summary (adjusted for actual fuel pressure). It seems to work OK but I'm never sure if I'm using the right data or not.

I'm attaching the injector data I used along with my adjustments for 55PSi base FP. Feel free to check my math! Let me know which calibration data you use and how it works out!
Sean

I don't have enough junk to worry about losing anything (did I just say that? ) I am a seasonal user, since my car doesn't come out in the wet, cold season. Just discovered that the online record of my progress here is no more. I will spend more time reading my hand-written notes (yes, I'm that old) and trying to remember where I left off. I'm grateful there is still somewhere to go with my questions when I'm stuck.

Sean